July 20, 2005
Elvia H. Thompson
Headquarters, Washington
(Phone: 202/358-1696)
Katherine K. Martin
Glenn Research Center, Cleveland
(Phone: 216/433-2406)
RELEASE: 05-191
NEW NASA DESIGN CONCEPT SMOKES OUT FALSE ALARMS
NASA researchers have successfully tested a new generation of fire
detectors that could significantly reduce the rate of false alarms in
the cargo and baggage compartments of commercial airliners.
The new sensor-based system was developed at NASA's Glenn Research
Center (GRC), Cleveland. It reads a more complete fire signature, and
it is so sensitive it may reduce false alarm rates to zero.
Most detectors sense smoke particles. They can be fooled by dust and
other tiny airborne particles found in non-passenger an aircraft
compartment, which leads to false alarms. The team at GRC used
MicroElectroMechanical Systems (MEMS) expertise to come up with a new
multi-sensor approach.
"We looked for increased concentrations of combustion gases along with
the smoke," said Gary Hunter, a Sensors and Electronics Branch
aerospace engineer. "The multi-sensor package compares various gas
concentrations and smoke particle sizes to those values
characteristic of an actual fire. The result is a system that works
to effectively recognize the presence of fire while screening out
false alarms."
The MEMS sensor system includes miniaturized carbon monoxide and
carbon dioxide sensors, a smoke particle detector and integrated
software. These compact arrays can be placed in multiple locations
throughout the aircraft's cargo and baggage compartments. The
on-board processor evaluates the response of the complete sensor
system and indicates whether there is a fire.
Fire alarms signal pilots to initiate emergency procedures. A Federal
Aviation Administration (FAA) survey of airline maintenance reports
has estimated that 100-200 false alarms occur for every actual fire.
In-flight fires are rare, but there is no way for flight crews to
verify sensor readings to know for sure a fire has started in a
remote compartment. So every alarm must be taken as seriously. This
means using extinguishing equipment, declaring emergency priority
over other air traffic and, landing as soon as possible.
GRC researchers teamed with colleagues from Case Western Reserve
University, Cleveland; Ohio State University, Columbus; and Makel
Engineering, Inc., Chico, Calif.; in collaboration with the FAA.
Tests conducted at the FAA Cargo Compartment Fire Testing Facility in
Atlantic City, N.J., successfully demonstrated the miniaturized,
combined chemical and particle sensors approach. NASA's multi-sensor
package had a zero false alarm rate when exposed to conditions that
would normally cause cargo compartment detectors to false alarm.
Further testing alongside conventional smoke detectors in the FAA's
Boeing 707 under-floor cargo bay showed the system detected fire as
well as conventional smoke detectors.
Before the new system can be installed on airplanes, the sensors,
software packaging and interface, long-term durability and drift
effects need to be improved and certified by the FAA. NASA's Aviation
Safety and Security Program sponsored the research as part of a joint
NASA-FAA program. Industrial Research and Development Magazine
recognized the effort as one of 100 best technical research and
development achievements of the year.
False alarms are also a concern in International Space Station
operations and during space exploration missions, so NASA is sharing
this research with spacecraft developers.
For information about NASA's Aviation Safety and Security Program on
the Web, visit:
http://www.grc.nasa.gov/WWW/avsp/accident.htm
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